Hunting ghosts in the sky

In June 2019, scientists from Spain They went looking for ghosts Which roamed the skies of the Mediterranean Sea. These green wisps, which dance on reddish-pink lightning at high altitudes during thunderstorms, were only discovered in May of that year. What were they? The only way to find out is to pick one up.

But the task will be difficult. Those ghosts They have a very appropriate name: It is difficult to see with the naked eye and is visible Just for a second Tens of kilometers from the ground.

“Seeing the ghost is very difficult,” said Maria Passas Faro, a researcher at the Andalusian Institute of Astrophysics in Spain.

But on September 21, 2019, finally They caught one With a specialized camera: A green spirit flashes in the crown of the whirlwind Fuchsia lightning with Jellyfish shape 80 kilometers above sea level. After detecting the different wavelengths of light emanating from the ghost, scientists revealed its elemental composition.

In a study published Tuesday in the journal Nature Communications, Passas-Faro and his colleagues revealed this The pale emerald skin of the ghost It came partly from excited oxygen, similar to the green glow of the northern lights; Nitrogen also plays a role.

But the main factor contributing to this was another element: Iron. It was a surprise, because The metal came from space.

A better understanding of ghosts and other ephemeral, lightning-like entities could help scientists Interpreting the chemistry and physics of the Earth’s upper atmosphereIt is difficult to decipher.

“There are layers of metal dancing” inside and above thunderstorms, Passas-Faro explained.

Ghosts are A type of transient light event, or ELT, which scientists first described in 1989. ELTs can include blue jets, shooting upwards from storm clouds, as well as crimson lightning in the upper atmosphere that can take many forms, such as islands and jellyfish, which are known as ELTs. . like ghost.

ELTs are “like fireworks,” Passas-Faro explained. Not much is known for sure about them, especially the ghosts, the first of which was seen above a ghostly storm over Oklahoma in May 2019.

To capture your ghost, team Spectral camera indicated — a device that can use light to determine chemistry — was beamed into the upper atmosphere from a monitoring point in Castillegalli, Spain. All they can do is wait for the ghost storms to appear, crossing their fingers and hoping that at least one of them will briefly be ghosted, and have their camera pointed at the right place.

finally, They found one hovering above a jellyfish creature.

“It was a matter of luck,” Passas-Faro said.

This was largely powered by extraterrestrial iron, not atmospheric oxygen. The camera also revealed the presence of nickel, sodium and silicon. The complex chemical soup responsible for this ghost even added a yellow-orange hue to its green glow.

All of these elements usually come from micrometeorites and particles from micrometeorites Deep space dust Which almost always falls into the upper atmosphere. This means that ghosts can be looked into effectively Interplanetary visitors.

However, some researchers said too many conclusions should not be drawn from the results of the new work.

“The metallic traces are interesting, but you have to be careful that this is a single case,” said Chris Vagaski, a lightning researcher at the University of Wisconsin-Madison who was not involved in the new work.

To find out if all the ghosts are iron-fueled ghosts, he added, “it would be nice to see the results of multiple ghosts.”

He has no doubt that the hunt for ghosts and other ELTs will continue, largely because such ghosts are inherently seductive.

“It’s really amazing to think that more things happen during a thunderstorm than you can see or hear,” Vagaski said.

c.2023 The New York Times Company

Translated by: Elisa Carneli